The present invention is related, in general, to methods involving electromagnetic forcing impact upon conducting media, and in particular, to such methods that can be applied for profound intensification of metallurgical processes.
Methods of forcing influence upon conducting media using rotating, traveling, or helically traveling magnetic fields are well known and sufficiently widely used for the intensification of various metallurgical processes, such as melting, alloying, purification from detrimental impurities, crystallization of continuous ingots and castings, etc. However, metallurgical process rates and final product quality obtained using the known methods can be considerably increased using the proposed method.
Methods of controlling the crystalline structure of continuous and stationary ingots and castings using rotating or traveling magnetic fields have been known since long ago (patents by Kürt (German Patent No. 307225, 1917), Jungans and Schaber (FRG Patent No. 911425, 1954), Pestel et al. (U.S. Pat. No. 2,963,758, 1960), each of which is hereby incorporated by reference in its entirety). Experimental material accumulated in this field shows that the application of rotating or traveling magnetic fields eliminates the columnar structure of cast products and makes it possible to produce ingots and castings with equiaxial fine-grain dense structures, which positively affects their mechanical properties. However, turbulence level in liquid metals achieved by conventional methods limits the application range of magnetohydrodynamic (MHD) impact in metallurgical technologies.
Therefore, a significant increase in the efficiency of the methods of MHD impact on melts in the process of their crystallization is a rather urgent problem.
In a related field, there is a known method of continuous tratment of cast iron melts in a rotating magnetic field (RMF) excited by non-modulated three-phase currents in facilities built for this purpose. These facilities are made in the form of an inclined lined channel with a receiving funnel and a ladle lip, around which explicit-pole inductors exciting RMF in the melt are arranged.
The maximal desulfurization rate attained in this facility using soda ash and magnesium powder in the capacity of desulfurizers amounts to about 10 relative % per second, and about 50% of the sulphur was removed. At the facility productivity of about 120 tons per hour was achieved, and electric energy consumption amounts to about 2 kilowatt hours per ton.
Despite relatively good technological results achieved on such a facility, the absolute desulfurization depth is relatively low, and thermal losses are very high due to the impossibility of applying a sufficiently thick lining in the mentioned facility.
In another related field, in typical channel induction furnaces, the melt located in the furnace shaft is stirred mainly at the expense of thermal convection, because the melt in the channels is always overheated in comparison with the melt in the shaft. Furthermore, in the upper part of the channels, a certain pressure gradient appears directed towards the shaft and connected with the inhomogeneity of the induced current density field. The intensity of melt stirring in the shaft is low, which increases the time duration required for the homogenization of the melt temperature and composition in the furnace, and prevents an increase in the furnace capacity at the expense of increasing the shaft height. It would be desirable to increase the intensity of melt stirring, thereby reducing the time required to process the melt.